The present invention relates to a chain saw bar having at its free end a sprocket supporting the saw chain and being rotatably mounted between two side plates in the saw bar on a tubular shaft, which is rigidly connected to the sprocket and is adapted to transfer rotation to a driven shaft inserted into the tubular shaft, bearing means being arranged in both side plates rotatably supporting the tubular shaft.
A chain saw of the present type consists of a motor unit, inclusive of controls, centrifugal coupling, driving wheel and an electric motor or a combustion motor, a bar unit comprising a bar having a sprocket at the outer end and a chain consisting of drive links, cutter links and side links. The primary field of use for the chain saw is felling and cutting up trees.
The motor unit is a strong power source which is easy to move, properties which render it suitable for many other working tasks, e.g. within agriculture and forestry. It has therefor been proposed to equip the motor unit with different accessory devices for such alternative fields of use. Such accessory devices require the removal of the bar unit and the chain and substitution of other specially designed devices or mounting special drive means parallel with the chain used for sawing. Examples of such constructions are described in U.S. Pat. Nos. 2,489,772, 2,708,468, 2,783,794, 2,821,216 and 4,188,987 and Swedish patent Nos. 87 829, 199400 and 7312617-9.
As distinguished from said prior devices the present invention aims at creating a bar unit which can be used both for its primary purpose, i.e. felling and cutting trees, and be equipped with accessory devices of different kinds. It is possible to attach the accessory equipment to the bar unit without having to change the chain or to remove hoods and other parts from the motor unit. In a bar unit of this type the end sprocket is thin and is surrounded on both sides by the side plates. The thickness of the bearing of the end sprocket is only slightly greater than the thickness of the rest of the bar unit and lies within the width of the saw kerf, so that nothing prevents the saw bar unit from being used for sawing when the accessory equipment is removed.
These and other purposes of the invention have been achieved by making the tubular shaft short enough to be inserted into a kerf made by a saw chain mounted on the saw bar.